xref: /openbmc/linux/fs/9p/vfs_inode.c (revision 77d84ff8)
1 /*
2  *  linux/fs/9p/vfs_inode.c
3  *
4  * This file contains vfs inode ops for the 9P2000 protocol.
5  *
6  *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
7  *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
8  *
9  *  This program is free software; you can redistribute it and/or modify
10  *  it under the terms of the GNU General Public License version 2
11  *  as published by the Free Software Foundation.
12  *
13  *  This program is distributed in the hope that it will be useful,
14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16  *  GNU General Public License for more details.
17  *
18  *  You should have received a copy of the GNU General Public License
19  *  along with this program; if not, write to:
20  *  Free Software Foundation
21  *  51 Franklin Street, Fifth Floor
22  *  Boston, MA  02111-1301  USA
23  *
24  */
25 
26 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
27 
28 #include <linux/module.h>
29 #include <linux/errno.h>
30 #include <linux/fs.h>
31 #include <linux/file.h>
32 #include <linux/pagemap.h>
33 #include <linux/stat.h>
34 #include <linux/string.h>
35 #include <linux/inet.h>
36 #include <linux/namei.h>
37 #include <linux/idr.h>
38 #include <linux/sched.h>
39 #include <linux/slab.h>
40 #include <linux/xattr.h>
41 #include <linux/posix_acl.h>
42 #include <net/9p/9p.h>
43 #include <net/9p/client.h>
44 
45 #include "v9fs.h"
46 #include "v9fs_vfs.h"
47 #include "fid.h"
48 #include "cache.h"
49 #include "xattr.h"
50 #include "acl.h"
51 
52 static const struct inode_operations v9fs_dir_inode_operations;
53 static const struct inode_operations v9fs_dir_inode_operations_dotu;
54 static const struct inode_operations v9fs_file_inode_operations;
55 static const struct inode_operations v9fs_symlink_inode_operations;
56 
57 /**
58  * unixmode2p9mode - convert unix mode bits to plan 9
59  * @v9ses: v9fs session information
60  * @mode: mode to convert
61  *
62  */
63 
64 static u32 unixmode2p9mode(struct v9fs_session_info *v9ses, umode_t mode)
65 {
66 	int res;
67 	res = mode & 0777;
68 	if (S_ISDIR(mode))
69 		res |= P9_DMDIR;
70 	if (v9fs_proto_dotu(v9ses)) {
71 		if (v9ses->nodev == 0) {
72 			if (S_ISSOCK(mode))
73 				res |= P9_DMSOCKET;
74 			if (S_ISFIFO(mode))
75 				res |= P9_DMNAMEDPIPE;
76 			if (S_ISBLK(mode))
77 				res |= P9_DMDEVICE;
78 			if (S_ISCHR(mode))
79 				res |= P9_DMDEVICE;
80 		}
81 
82 		if ((mode & S_ISUID) == S_ISUID)
83 			res |= P9_DMSETUID;
84 		if ((mode & S_ISGID) == S_ISGID)
85 			res |= P9_DMSETGID;
86 		if ((mode & S_ISVTX) == S_ISVTX)
87 			res |= P9_DMSETVTX;
88 	}
89 	return res;
90 }
91 
92 /**
93  * p9mode2perm- convert plan9 mode bits to unix permission bits
94  * @v9ses: v9fs session information
95  * @stat: p9_wstat from which mode need to be derived
96  *
97  */
98 static int p9mode2perm(struct v9fs_session_info *v9ses,
99 		       struct p9_wstat *stat)
100 {
101 	int res;
102 	int mode = stat->mode;
103 
104 	res = mode & S_IALLUGO;
105 	if (v9fs_proto_dotu(v9ses)) {
106 		if ((mode & P9_DMSETUID) == P9_DMSETUID)
107 			res |= S_ISUID;
108 
109 		if ((mode & P9_DMSETGID) == P9_DMSETGID)
110 			res |= S_ISGID;
111 
112 		if ((mode & P9_DMSETVTX) == P9_DMSETVTX)
113 			res |= S_ISVTX;
114 	}
115 	return res;
116 }
117 
118 /**
119  * p9mode2unixmode- convert plan9 mode bits to unix mode bits
120  * @v9ses: v9fs session information
121  * @stat: p9_wstat from which mode need to be derived
122  * @rdev: major number, minor number in case of device files.
123  *
124  */
125 static umode_t p9mode2unixmode(struct v9fs_session_info *v9ses,
126 			       struct p9_wstat *stat, dev_t *rdev)
127 {
128 	int res;
129 	u32 mode = stat->mode;
130 
131 	*rdev = 0;
132 	res = p9mode2perm(v9ses, stat);
133 
134 	if ((mode & P9_DMDIR) == P9_DMDIR)
135 		res |= S_IFDIR;
136 	else if ((mode & P9_DMSYMLINK) && (v9fs_proto_dotu(v9ses)))
137 		res |= S_IFLNK;
138 	else if ((mode & P9_DMSOCKET) && (v9fs_proto_dotu(v9ses))
139 		 && (v9ses->nodev == 0))
140 		res |= S_IFSOCK;
141 	else if ((mode & P9_DMNAMEDPIPE) && (v9fs_proto_dotu(v9ses))
142 		 && (v9ses->nodev == 0))
143 		res |= S_IFIFO;
144 	else if ((mode & P9_DMDEVICE) && (v9fs_proto_dotu(v9ses))
145 		 && (v9ses->nodev == 0)) {
146 		char type = 0, ext[32];
147 		int major = -1, minor = -1;
148 
149 		strlcpy(ext, stat->extension, sizeof(ext));
150 		sscanf(ext, "%c %u %u", &type, &major, &minor);
151 		switch (type) {
152 		case 'c':
153 			res |= S_IFCHR;
154 			break;
155 		case 'b':
156 			res |= S_IFBLK;
157 			break;
158 		default:
159 			p9_debug(P9_DEBUG_ERROR, "Unknown special type %c %s\n",
160 				 type, stat->extension);
161 		};
162 		*rdev = MKDEV(major, minor);
163 	} else
164 		res |= S_IFREG;
165 
166 	return res;
167 }
168 
169 /**
170  * v9fs_uflags2omode- convert posix open flags to plan 9 mode bits
171  * @uflags: flags to convert
172  * @extended: if .u extensions are active
173  */
174 
175 int v9fs_uflags2omode(int uflags, int extended)
176 {
177 	int ret;
178 
179 	ret = 0;
180 	switch (uflags&3) {
181 	default:
182 	case O_RDONLY:
183 		ret = P9_OREAD;
184 		break;
185 
186 	case O_WRONLY:
187 		ret = P9_OWRITE;
188 		break;
189 
190 	case O_RDWR:
191 		ret = P9_ORDWR;
192 		break;
193 	}
194 
195 	if (extended) {
196 		if (uflags & O_EXCL)
197 			ret |= P9_OEXCL;
198 
199 		if (uflags & O_APPEND)
200 			ret |= P9_OAPPEND;
201 	}
202 
203 	return ret;
204 }
205 
206 /**
207  * v9fs_blank_wstat - helper function to setup a 9P stat structure
208  * @wstat: structure to initialize
209  *
210  */
211 
212 void
213 v9fs_blank_wstat(struct p9_wstat *wstat)
214 {
215 	wstat->type = ~0;
216 	wstat->dev = ~0;
217 	wstat->qid.type = ~0;
218 	wstat->qid.version = ~0;
219 	*((long long *)&wstat->qid.path) = ~0;
220 	wstat->mode = ~0;
221 	wstat->atime = ~0;
222 	wstat->mtime = ~0;
223 	wstat->length = ~0;
224 	wstat->name = NULL;
225 	wstat->uid = NULL;
226 	wstat->gid = NULL;
227 	wstat->muid = NULL;
228 	wstat->n_uid = INVALID_UID;
229 	wstat->n_gid = INVALID_GID;
230 	wstat->n_muid = INVALID_UID;
231 	wstat->extension = NULL;
232 }
233 
234 /**
235  * v9fs_alloc_inode - helper function to allocate an inode
236  *
237  */
238 struct inode *v9fs_alloc_inode(struct super_block *sb)
239 {
240 	struct v9fs_inode *v9inode;
241 	v9inode = (struct v9fs_inode *)kmem_cache_alloc(v9fs_inode_cache,
242 							GFP_KERNEL);
243 	if (!v9inode)
244 		return NULL;
245 #ifdef CONFIG_9P_FSCACHE
246 	v9inode->fscache = NULL;
247 	spin_lock_init(&v9inode->fscache_lock);
248 #endif
249 	v9inode->writeback_fid = NULL;
250 	v9inode->cache_validity = 0;
251 	mutex_init(&v9inode->v_mutex);
252 	return &v9inode->vfs_inode;
253 }
254 
255 /**
256  * v9fs_destroy_inode - destroy an inode
257  *
258  */
259 
260 static void v9fs_i_callback(struct rcu_head *head)
261 {
262 	struct inode *inode = container_of(head, struct inode, i_rcu);
263 	kmem_cache_free(v9fs_inode_cache, V9FS_I(inode));
264 }
265 
266 void v9fs_destroy_inode(struct inode *inode)
267 {
268 	call_rcu(&inode->i_rcu, v9fs_i_callback);
269 }
270 
271 int v9fs_init_inode(struct v9fs_session_info *v9ses,
272 		    struct inode *inode, umode_t mode, dev_t rdev)
273 {
274 	int err = 0;
275 
276 	inode_init_owner(inode, NULL, mode);
277 	inode->i_blocks = 0;
278 	inode->i_rdev = rdev;
279 	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
280 	inode->i_mapping->a_ops = &v9fs_addr_operations;
281 
282 	switch (mode & S_IFMT) {
283 	case S_IFIFO:
284 	case S_IFBLK:
285 	case S_IFCHR:
286 	case S_IFSOCK:
287 		if (v9fs_proto_dotl(v9ses)) {
288 			inode->i_op = &v9fs_file_inode_operations_dotl;
289 		} else if (v9fs_proto_dotu(v9ses)) {
290 			inode->i_op = &v9fs_file_inode_operations;
291 		} else {
292 			p9_debug(P9_DEBUG_ERROR,
293 				 "special files without extended mode\n");
294 			err = -EINVAL;
295 			goto error;
296 		}
297 		init_special_inode(inode, inode->i_mode, inode->i_rdev);
298 		break;
299 	case S_IFREG:
300 		if (v9fs_proto_dotl(v9ses)) {
301 			inode->i_op = &v9fs_file_inode_operations_dotl;
302 			if (v9ses->cache)
303 				inode->i_fop =
304 					&v9fs_cached_file_operations_dotl;
305 			else
306 				inode->i_fop = &v9fs_file_operations_dotl;
307 		} else {
308 			inode->i_op = &v9fs_file_inode_operations;
309 			if (v9ses->cache)
310 				inode->i_fop = &v9fs_cached_file_operations;
311 			else
312 				inode->i_fop = &v9fs_file_operations;
313 		}
314 
315 		break;
316 	case S_IFLNK:
317 		if (!v9fs_proto_dotu(v9ses) && !v9fs_proto_dotl(v9ses)) {
318 			p9_debug(P9_DEBUG_ERROR,
319 				 "extended modes used with legacy protocol\n");
320 			err = -EINVAL;
321 			goto error;
322 		}
323 
324 		if (v9fs_proto_dotl(v9ses))
325 			inode->i_op = &v9fs_symlink_inode_operations_dotl;
326 		else
327 			inode->i_op = &v9fs_symlink_inode_operations;
328 
329 		break;
330 	case S_IFDIR:
331 		inc_nlink(inode);
332 		if (v9fs_proto_dotl(v9ses))
333 			inode->i_op = &v9fs_dir_inode_operations_dotl;
334 		else if (v9fs_proto_dotu(v9ses))
335 			inode->i_op = &v9fs_dir_inode_operations_dotu;
336 		else
337 			inode->i_op = &v9fs_dir_inode_operations;
338 
339 		if (v9fs_proto_dotl(v9ses))
340 			inode->i_fop = &v9fs_dir_operations_dotl;
341 		else
342 			inode->i_fop = &v9fs_dir_operations;
343 
344 		break;
345 	default:
346 		p9_debug(P9_DEBUG_ERROR, "BAD mode 0x%hx S_IFMT 0x%x\n",
347 			 mode, mode & S_IFMT);
348 		err = -EINVAL;
349 		goto error;
350 	}
351 error:
352 	return err;
353 
354 }
355 
356 /**
357  * v9fs_get_inode - helper function to setup an inode
358  * @sb: superblock
359  * @mode: mode to setup inode with
360  *
361  */
362 
363 struct inode *v9fs_get_inode(struct super_block *sb, umode_t mode, dev_t rdev)
364 {
365 	int err;
366 	struct inode *inode;
367 	struct v9fs_session_info *v9ses = sb->s_fs_info;
368 
369 	p9_debug(P9_DEBUG_VFS, "super block: %p mode: %ho\n", sb, mode);
370 
371 	inode = new_inode(sb);
372 	if (!inode) {
373 		pr_warn("%s (%d): Problem allocating inode\n",
374 			__func__, task_pid_nr(current));
375 		return ERR_PTR(-ENOMEM);
376 	}
377 	err = v9fs_init_inode(v9ses, inode, mode, rdev);
378 	if (err) {
379 		iput(inode);
380 		return ERR_PTR(err);
381 	}
382 	return inode;
383 }
384 
385 /*
386 static struct v9fs_fid*
387 v9fs_clone_walk(struct v9fs_session_info *v9ses, u32 fid, struct dentry *dentry)
388 {
389 	int err;
390 	int nfid;
391 	struct v9fs_fid *ret;
392 	struct v9fs_fcall *fcall;
393 
394 	nfid = v9fs_get_idpool(&v9ses->fidpool);
395 	if (nfid < 0) {
396 		eprintk(KERN_WARNING, "no free fids available\n");
397 		return ERR_PTR(-ENOSPC);
398 	}
399 
400 	err = v9fs_t_walk(v9ses, fid, nfid, (char *) dentry->d_name.name,
401 		&fcall);
402 
403 	if (err < 0) {
404 		if (fcall && fcall->id == RWALK)
405 			goto clunk_fid;
406 
407 		PRINT_FCALL_ERROR("walk error", fcall);
408 		v9fs_put_idpool(nfid, &v9ses->fidpool);
409 		goto error;
410 	}
411 
412 	kfree(fcall);
413 	fcall = NULL;
414 	ret = v9fs_fid_create(v9ses, nfid);
415 	if (!ret) {
416 		err = -ENOMEM;
417 		goto clunk_fid;
418 	}
419 
420 	err = v9fs_fid_insert(ret, dentry);
421 	if (err < 0) {
422 		v9fs_fid_destroy(ret);
423 		goto clunk_fid;
424 	}
425 
426 	return ret;
427 
428 clunk_fid:
429 	v9fs_t_clunk(v9ses, nfid);
430 
431 error:
432 	kfree(fcall);
433 	return ERR_PTR(err);
434 }
435 */
436 
437 
438 /**
439  * v9fs_clear_inode - release an inode
440  * @inode: inode to release
441  *
442  */
443 void v9fs_evict_inode(struct inode *inode)
444 {
445 	struct v9fs_inode *v9inode = V9FS_I(inode);
446 
447 	truncate_inode_pages(inode->i_mapping, 0);
448 	clear_inode(inode);
449 	filemap_fdatawrite(inode->i_mapping);
450 
451 	v9fs_cache_inode_put_cookie(inode);
452 	/* clunk the fid stashed in writeback_fid */
453 	if (v9inode->writeback_fid) {
454 		p9_client_clunk(v9inode->writeback_fid);
455 		v9inode->writeback_fid = NULL;
456 	}
457 }
458 
459 static int v9fs_test_inode(struct inode *inode, void *data)
460 {
461 	int umode;
462 	dev_t rdev;
463 	struct v9fs_inode *v9inode = V9FS_I(inode);
464 	struct p9_wstat *st = (struct p9_wstat *)data;
465 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
466 
467 	umode = p9mode2unixmode(v9ses, st, &rdev);
468 	/* don't match inode of different type */
469 	if ((inode->i_mode & S_IFMT) != (umode & S_IFMT))
470 		return 0;
471 
472 	/* compare qid details */
473 	if (memcmp(&v9inode->qid.version,
474 		   &st->qid.version, sizeof(v9inode->qid.version)))
475 		return 0;
476 
477 	if (v9inode->qid.type != st->qid.type)
478 		return 0;
479 	return 1;
480 }
481 
482 static int v9fs_test_new_inode(struct inode *inode, void *data)
483 {
484 	return 0;
485 }
486 
487 static int v9fs_set_inode(struct inode *inode,  void *data)
488 {
489 	struct v9fs_inode *v9inode = V9FS_I(inode);
490 	struct p9_wstat *st = (struct p9_wstat *)data;
491 
492 	memcpy(&v9inode->qid, &st->qid, sizeof(st->qid));
493 	return 0;
494 }
495 
496 static struct inode *v9fs_qid_iget(struct super_block *sb,
497 				   struct p9_qid *qid,
498 				   struct p9_wstat *st,
499 				   int new)
500 {
501 	dev_t rdev;
502 	int retval;
503 	umode_t umode;
504 	unsigned long i_ino;
505 	struct inode *inode;
506 	struct v9fs_session_info *v9ses = sb->s_fs_info;
507 	int (*test)(struct inode *, void *);
508 
509 	if (new)
510 		test = v9fs_test_new_inode;
511 	else
512 		test = v9fs_test_inode;
513 
514 	i_ino = v9fs_qid2ino(qid);
515 	inode = iget5_locked(sb, i_ino, test, v9fs_set_inode, st);
516 	if (!inode)
517 		return ERR_PTR(-ENOMEM);
518 	if (!(inode->i_state & I_NEW))
519 		return inode;
520 	/*
521 	 * initialize the inode with the stat info
522 	 * FIXME!! we may need support for stale inodes
523 	 * later.
524 	 */
525 	inode->i_ino = i_ino;
526 	umode = p9mode2unixmode(v9ses, st, &rdev);
527 	retval = v9fs_init_inode(v9ses, inode, umode, rdev);
528 	if (retval)
529 		goto error;
530 
531 	v9fs_stat2inode(st, inode, sb);
532 	v9fs_cache_inode_get_cookie(inode);
533 	unlock_new_inode(inode);
534 	return inode;
535 error:
536 	unlock_new_inode(inode);
537 	iput(inode);
538 	return ERR_PTR(retval);
539 
540 }
541 
542 struct inode *
543 v9fs_inode_from_fid(struct v9fs_session_info *v9ses, struct p9_fid *fid,
544 		    struct super_block *sb, int new)
545 {
546 	struct p9_wstat *st;
547 	struct inode *inode = NULL;
548 
549 	st = p9_client_stat(fid);
550 	if (IS_ERR(st))
551 		return ERR_CAST(st);
552 
553 	inode = v9fs_qid_iget(sb, &st->qid, st, new);
554 	p9stat_free(st);
555 	kfree(st);
556 	return inode;
557 }
558 
559 /**
560  * v9fs_at_to_dotl_flags- convert Linux specific AT flags to
561  * plan 9 AT flag.
562  * @flags: flags to convert
563  */
564 static int v9fs_at_to_dotl_flags(int flags)
565 {
566 	int rflags = 0;
567 	if (flags & AT_REMOVEDIR)
568 		rflags |= P9_DOTL_AT_REMOVEDIR;
569 	return rflags;
570 }
571 
572 /**
573  * v9fs_remove - helper function to remove files and directories
574  * @dir: directory inode that is being deleted
575  * @dentry:  dentry that is being deleted
576  * @rmdir: removing a directory
577  *
578  */
579 
580 static int v9fs_remove(struct inode *dir, struct dentry *dentry, int flags)
581 {
582 	struct inode *inode;
583 	int retval = -EOPNOTSUPP;
584 	struct p9_fid *v9fid, *dfid;
585 	struct v9fs_session_info *v9ses;
586 
587 	p9_debug(P9_DEBUG_VFS, "inode: %p dentry: %p rmdir: %x\n",
588 		 dir, dentry, flags);
589 
590 	v9ses = v9fs_inode2v9ses(dir);
591 	inode = dentry->d_inode;
592 	dfid = v9fs_fid_lookup(dentry->d_parent);
593 	if (IS_ERR(dfid)) {
594 		retval = PTR_ERR(dfid);
595 		p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", retval);
596 		return retval;
597 	}
598 	if (v9fs_proto_dotl(v9ses))
599 		retval = p9_client_unlinkat(dfid, dentry->d_name.name,
600 					    v9fs_at_to_dotl_flags(flags));
601 	if (retval == -EOPNOTSUPP) {
602 		/* Try the one based on path */
603 		v9fid = v9fs_fid_clone(dentry);
604 		if (IS_ERR(v9fid))
605 			return PTR_ERR(v9fid);
606 		retval = p9_client_remove(v9fid);
607 	}
608 	if (!retval) {
609 		/*
610 		 * directories on unlink should have zero
611 		 * link count
612 		 */
613 		if (flags & AT_REMOVEDIR) {
614 			clear_nlink(inode);
615 			drop_nlink(dir);
616 		} else
617 			drop_nlink(inode);
618 
619 		v9fs_invalidate_inode_attr(inode);
620 		v9fs_invalidate_inode_attr(dir);
621 	}
622 	return retval;
623 }
624 
625 /**
626  * v9fs_create - Create a file
627  * @v9ses: session information
628  * @dir: directory that dentry is being created in
629  * @dentry:  dentry that is being created
630  * @extension: 9p2000.u extension string to support devices, etc.
631  * @perm: create permissions
632  * @mode: open mode
633  *
634  */
635 static struct p9_fid *
636 v9fs_create(struct v9fs_session_info *v9ses, struct inode *dir,
637 		struct dentry *dentry, char *extension, u32 perm, u8 mode)
638 {
639 	int err;
640 	char *name;
641 	struct p9_fid *dfid, *ofid, *fid;
642 	struct inode *inode;
643 
644 	p9_debug(P9_DEBUG_VFS, "name %s\n", dentry->d_name.name);
645 
646 	err = 0;
647 	ofid = NULL;
648 	fid = NULL;
649 	name = (char *) dentry->d_name.name;
650 	dfid = v9fs_fid_lookup(dentry->d_parent);
651 	if (IS_ERR(dfid)) {
652 		err = PTR_ERR(dfid);
653 		p9_debug(P9_DEBUG_VFS, "fid lookup failed %d\n", err);
654 		return ERR_PTR(err);
655 	}
656 
657 	/* clone a fid to use for creation */
658 	ofid = p9_client_walk(dfid, 0, NULL, 1);
659 	if (IS_ERR(ofid)) {
660 		err = PTR_ERR(ofid);
661 		p9_debug(P9_DEBUG_VFS, "p9_client_walk failed %d\n", err);
662 		return ERR_PTR(err);
663 	}
664 
665 	err = p9_client_fcreate(ofid, name, perm, mode, extension);
666 	if (err < 0) {
667 		p9_debug(P9_DEBUG_VFS, "p9_client_fcreate failed %d\n", err);
668 		goto error;
669 	}
670 
671 	if (!(perm & P9_DMLINK)) {
672 		/* now walk from the parent so we can get unopened fid */
673 		fid = p9_client_walk(dfid, 1, &name, 1);
674 		if (IS_ERR(fid)) {
675 			err = PTR_ERR(fid);
676 			p9_debug(P9_DEBUG_VFS,
677 				   "p9_client_walk failed %d\n", err);
678 			fid = NULL;
679 			goto error;
680 		}
681 		/*
682 		 * instantiate inode and assign the unopened fid to the dentry
683 		 */
684 		inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
685 		if (IS_ERR(inode)) {
686 			err = PTR_ERR(inode);
687 			p9_debug(P9_DEBUG_VFS,
688 				   "inode creation failed %d\n", err);
689 			goto error;
690 		}
691 		v9fs_fid_add(dentry, fid);
692 		d_instantiate(dentry, inode);
693 	}
694 	return ofid;
695 error:
696 	if (ofid)
697 		p9_client_clunk(ofid);
698 
699 	if (fid)
700 		p9_client_clunk(fid);
701 
702 	return ERR_PTR(err);
703 }
704 
705 /**
706  * v9fs_vfs_create - VFS hook to create a regular file
707  *
708  * open(.., O_CREAT) is handled in v9fs_vfs_atomic_open().  This is only called
709  * for mknod(2).
710  *
711  * @dir: directory inode that is being created
712  * @dentry:  dentry that is being deleted
713  * @mode: create permissions
714  *
715  */
716 
717 static int
718 v9fs_vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
719 		bool excl)
720 {
721 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
722 	u32 perm = unixmode2p9mode(v9ses, mode);
723 	struct p9_fid *fid;
724 
725 	/* P9_OEXCL? */
726 	fid = v9fs_create(v9ses, dir, dentry, NULL, perm, P9_ORDWR);
727 	if (IS_ERR(fid))
728 		return PTR_ERR(fid);
729 
730 	v9fs_invalidate_inode_attr(dir);
731 	p9_client_clunk(fid);
732 
733 	return 0;
734 }
735 
736 /**
737  * v9fs_vfs_mkdir - VFS mkdir hook to create a directory
738  * @dir:  inode that is being unlinked
739  * @dentry: dentry that is being unlinked
740  * @mode: mode for new directory
741  *
742  */
743 
744 static int v9fs_vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
745 {
746 	int err;
747 	u32 perm;
748 	struct p9_fid *fid;
749 	struct v9fs_session_info *v9ses;
750 
751 	p9_debug(P9_DEBUG_VFS, "name %s\n", dentry->d_name.name);
752 	err = 0;
753 	v9ses = v9fs_inode2v9ses(dir);
754 	perm = unixmode2p9mode(v9ses, mode | S_IFDIR);
755 	fid = v9fs_create(v9ses, dir, dentry, NULL, perm, P9_OREAD);
756 	if (IS_ERR(fid)) {
757 		err = PTR_ERR(fid);
758 		fid = NULL;
759 	} else {
760 		inc_nlink(dir);
761 		v9fs_invalidate_inode_attr(dir);
762 	}
763 
764 	if (fid)
765 		p9_client_clunk(fid);
766 
767 	return err;
768 }
769 
770 /**
771  * v9fs_vfs_lookup - VFS lookup hook to "walk" to a new inode
772  * @dir:  inode that is being walked from
773  * @dentry: dentry that is being walked to?
774  * @nameidata: path data
775  *
776  */
777 
778 struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
779 				      unsigned int flags)
780 {
781 	struct dentry *res;
782 	struct super_block *sb;
783 	struct v9fs_session_info *v9ses;
784 	struct p9_fid *dfid, *fid;
785 	struct inode *inode;
786 	char *name;
787 
788 	p9_debug(P9_DEBUG_VFS, "dir: %p dentry: (%s) %p flags: %x\n",
789 		 dir, dentry->d_name.name, dentry, flags);
790 
791 	if (dentry->d_name.len > NAME_MAX)
792 		return ERR_PTR(-ENAMETOOLONG);
793 
794 	sb = dir->i_sb;
795 	v9ses = v9fs_inode2v9ses(dir);
796 	/* We can walk d_parent because we hold the dir->i_mutex */
797 	dfid = v9fs_fid_lookup(dentry->d_parent);
798 	if (IS_ERR(dfid))
799 		return ERR_CAST(dfid);
800 
801 	name = (char *) dentry->d_name.name;
802 	fid = p9_client_walk(dfid, 1, &name, 1);
803 	if (IS_ERR(fid)) {
804 		if (fid == ERR_PTR(-ENOENT)) {
805 			d_add(dentry, NULL);
806 			return NULL;
807 		}
808 		return ERR_CAST(fid);
809 	}
810 	/*
811 	 * Make sure we don't use a wrong inode due to parallel
812 	 * unlink. For cached mode create calls request for new
813 	 * inode. But with cache disabled, lookup should do this.
814 	 */
815 	if (v9ses->cache)
816 		inode = v9fs_get_inode_from_fid(v9ses, fid, dir->i_sb);
817 	else
818 		inode = v9fs_get_new_inode_from_fid(v9ses, fid, dir->i_sb);
819 	if (IS_ERR(inode)) {
820 		p9_client_clunk(fid);
821 		return ERR_CAST(inode);
822 	}
823 	/*
824 	 * If we had a rename on the server and a parallel lookup
825 	 * for the new name, then make sure we instantiate with
826 	 * the new name. ie look up for a/b, while on server somebody
827 	 * moved b under k and client parallely did a lookup for
828 	 * k/b.
829 	 */
830 	res = d_materialise_unique(dentry, inode);
831 	if (!res)
832 		v9fs_fid_add(dentry, fid);
833 	else if (!IS_ERR(res))
834 		v9fs_fid_add(res, fid);
835 	else
836 		p9_client_clunk(fid);
837 	return res;
838 }
839 
840 static int
841 v9fs_vfs_atomic_open(struct inode *dir, struct dentry *dentry,
842 		     struct file *file, unsigned flags, umode_t mode,
843 		     int *opened)
844 {
845 	int err;
846 	u32 perm;
847 	struct v9fs_inode *v9inode;
848 	struct v9fs_session_info *v9ses;
849 	struct p9_fid *fid, *inode_fid;
850 	struct dentry *res = NULL;
851 
852 	if (d_unhashed(dentry)) {
853 		res = v9fs_vfs_lookup(dir, dentry, 0);
854 		if (IS_ERR(res))
855 			return PTR_ERR(res);
856 
857 		if (res)
858 			dentry = res;
859 	}
860 
861 	/* Only creates */
862 	if (!(flags & O_CREAT) || dentry->d_inode)
863 		return finish_no_open(file, res);
864 
865 	err = 0;
866 	fid = NULL;
867 	v9ses = v9fs_inode2v9ses(dir);
868 	perm = unixmode2p9mode(v9ses, mode);
869 	fid = v9fs_create(v9ses, dir, dentry, NULL, perm,
870 				v9fs_uflags2omode(flags,
871 						v9fs_proto_dotu(v9ses)));
872 	if (IS_ERR(fid)) {
873 		err = PTR_ERR(fid);
874 		fid = NULL;
875 		goto error;
876 	}
877 
878 	v9fs_invalidate_inode_attr(dir);
879 	v9inode = V9FS_I(dentry->d_inode);
880 	mutex_lock(&v9inode->v_mutex);
881 	if (v9ses->cache && !v9inode->writeback_fid &&
882 	    ((flags & O_ACCMODE) != O_RDONLY)) {
883 		/*
884 		 * clone a fid and add it to writeback_fid
885 		 * we do it during open time instead of
886 		 * page dirty time via write_begin/page_mkwrite
887 		 * because we want write after unlink usecase
888 		 * to work.
889 		 */
890 		inode_fid = v9fs_writeback_fid(dentry);
891 		if (IS_ERR(inode_fid)) {
892 			err = PTR_ERR(inode_fid);
893 			mutex_unlock(&v9inode->v_mutex);
894 			goto error;
895 		}
896 		v9inode->writeback_fid = (void *) inode_fid;
897 	}
898 	mutex_unlock(&v9inode->v_mutex);
899 	err = finish_open(file, dentry, generic_file_open, opened);
900 	if (err)
901 		goto error;
902 
903 	file->private_data = fid;
904 	if (v9ses->cache)
905 		v9fs_cache_inode_set_cookie(dentry->d_inode, file);
906 
907 	*opened |= FILE_CREATED;
908 out:
909 	dput(res);
910 	return err;
911 
912 error:
913 	if (fid)
914 		p9_client_clunk(fid);
915 	goto out;
916 }
917 
918 /**
919  * v9fs_vfs_unlink - VFS unlink hook to delete an inode
920  * @i:  inode that is being unlinked
921  * @d: dentry that is being unlinked
922  *
923  */
924 
925 int v9fs_vfs_unlink(struct inode *i, struct dentry *d)
926 {
927 	return v9fs_remove(i, d, 0);
928 }
929 
930 /**
931  * v9fs_vfs_rmdir - VFS unlink hook to delete a directory
932  * @i:  inode that is being unlinked
933  * @d: dentry that is being unlinked
934  *
935  */
936 
937 int v9fs_vfs_rmdir(struct inode *i, struct dentry *d)
938 {
939 	return v9fs_remove(i, d, AT_REMOVEDIR);
940 }
941 
942 /**
943  * v9fs_vfs_rename - VFS hook to rename an inode
944  * @old_dir:  old dir inode
945  * @old_dentry: old dentry
946  * @new_dir: new dir inode
947  * @new_dentry: new dentry
948  *
949  */
950 
951 int
952 v9fs_vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
953 		struct inode *new_dir, struct dentry *new_dentry)
954 {
955 	int retval;
956 	struct inode *old_inode;
957 	struct inode *new_inode;
958 	struct v9fs_session_info *v9ses;
959 	struct p9_fid *oldfid;
960 	struct p9_fid *olddirfid;
961 	struct p9_fid *newdirfid;
962 	struct p9_wstat wstat;
963 
964 	p9_debug(P9_DEBUG_VFS, "\n");
965 	retval = 0;
966 	old_inode = old_dentry->d_inode;
967 	new_inode = new_dentry->d_inode;
968 	v9ses = v9fs_inode2v9ses(old_inode);
969 	oldfid = v9fs_fid_lookup(old_dentry);
970 	if (IS_ERR(oldfid))
971 		return PTR_ERR(oldfid);
972 
973 	olddirfid = v9fs_fid_clone(old_dentry->d_parent);
974 	if (IS_ERR(olddirfid)) {
975 		retval = PTR_ERR(olddirfid);
976 		goto done;
977 	}
978 
979 	newdirfid = v9fs_fid_clone(new_dentry->d_parent);
980 	if (IS_ERR(newdirfid)) {
981 		retval = PTR_ERR(newdirfid);
982 		goto clunk_olddir;
983 	}
984 
985 	down_write(&v9ses->rename_sem);
986 	if (v9fs_proto_dotl(v9ses)) {
987 		retval = p9_client_renameat(olddirfid, old_dentry->d_name.name,
988 					    newdirfid, new_dentry->d_name.name);
989 		if (retval == -EOPNOTSUPP)
990 			retval = p9_client_rename(oldfid, newdirfid,
991 						  new_dentry->d_name.name);
992 		if (retval != -EOPNOTSUPP)
993 			goto clunk_newdir;
994 	}
995 	if (old_dentry->d_parent != new_dentry->d_parent) {
996 		/*
997 		 * 9P .u can only handle file rename in the same directory
998 		 */
999 
1000 		p9_debug(P9_DEBUG_ERROR, "old dir and new dir are different\n");
1001 		retval = -EXDEV;
1002 		goto clunk_newdir;
1003 	}
1004 	v9fs_blank_wstat(&wstat);
1005 	wstat.muid = v9ses->uname;
1006 	wstat.name = (char *) new_dentry->d_name.name;
1007 	retval = p9_client_wstat(oldfid, &wstat);
1008 
1009 clunk_newdir:
1010 	if (!retval) {
1011 		if (new_inode) {
1012 			if (S_ISDIR(new_inode->i_mode))
1013 				clear_nlink(new_inode);
1014 			else
1015 				drop_nlink(new_inode);
1016 		}
1017 		if (S_ISDIR(old_inode->i_mode)) {
1018 			if (!new_inode)
1019 				inc_nlink(new_dir);
1020 			drop_nlink(old_dir);
1021 		}
1022 		v9fs_invalidate_inode_attr(old_inode);
1023 		v9fs_invalidate_inode_attr(old_dir);
1024 		v9fs_invalidate_inode_attr(new_dir);
1025 
1026 		/* successful rename */
1027 		d_move(old_dentry, new_dentry);
1028 	}
1029 	up_write(&v9ses->rename_sem);
1030 	p9_client_clunk(newdirfid);
1031 
1032 clunk_olddir:
1033 	p9_client_clunk(olddirfid);
1034 
1035 done:
1036 	return retval;
1037 }
1038 
1039 /**
1040  * v9fs_vfs_getattr - retrieve file metadata
1041  * @mnt: mount information
1042  * @dentry: file to get attributes on
1043  * @stat: metadata structure to populate
1044  *
1045  */
1046 
1047 static int
1048 v9fs_vfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
1049 		 struct kstat *stat)
1050 {
1051 	struct v9fs_session_info *v9ses;
1052 	struct p9_fid *fid;
1053 	struct p9_wstat *st;
1054 
1055 	p9_debug(P9_DEBUG_VFS, "dentry: %p\n", dentry);
1056 	v9ses = v9fs_dentry2v9ses(dentry);
1057 	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
1058 		generic_fillattr(dentry->d_inode, stat);
1059 		return 0;
1060 	}
1061 	fid = v9fs_fid_lookup(dentry);
1062 	if (IS_ERR(fid))
1063 		return PTR_ERR(fid);
1064 
1065 	st = p9_client_stat(fid);
1066 	if (IS_ERR(st))
1067 		return PTR_ERR(st);
1068 
1069 	v9fs_stat2inode(st, dentry->d_inode, dentry->d_inode->i_sb);
1070 	generic_fillattr(dentry->d_inode, stat);
1071 
1072 	p9stat_free(st);
1073 	kfree(st);
1074 	return 0;
1075 }
1076 
1077 /**
1078  * v9fs_vfs_setattr - set file metadata
1079  * @dentry: file whose metadata to set
1080  * @iattr: metadata assignment structure
1081  *
1082  */
1083 
1084 static int v9fs_vfs_setattr(struct dentry *dentry, struct iattr *iattr)
1085 {
1086 	int retval;
1087 	struct v9fs_session_info *v9ses;
1088 	struct p9_fid *fid;
1089 	struct p9_wstat wstat;
1090 
1091 	p9_debug(P9_DEBUG_VFS, "\n");
1092 	retval = inode_change_ok(dentry->d_inode, iattr);
1093 	if (retval)
1094 		return retval;
1095 
1096 	retval = -EPERM;
1097 	v9ses = v9fs_dentry2v9ses(dentry);
1098 	fid = v9fs_fid_lookup(dentry);
1099 	if(IS_ERR(fid))
1100 		return PTR_ERR(fid);
1101 
1102 	v9fs_blank_wstat(&wstat);
1103 	if (iattr->ia_valid & ATTR_MODE)
1104 		wstat.mode = unixmode2p9mode(v9ses, iattr->ia_mode);
1105 
1106 	if (iattr->ia_valid & ATTR_MTIME)
1107 		wstat.mtime = iattr->ia_mtime.tv_sec;
1108 
1109 	if (iattr->ia_valid & ATTR_ATIME)
1110 		wstat.atime = iattr->ia_atime.tv_sec;
1111 
1112 	if (iattr->ia_valid & ATTR_SIZE)
1113 		wstat.length = iattr->ia_size;
1114 
1115 	if (v9fs_proto_dotu(v9ses)) {
1116 		if (iattr->ia_valid & ATTR_UID)
1117 			wstat.n_uid = iattr->ia_uid;
1118 
1119 		if (iattr->ia_valid & ATTR_GID)
1120 			wstat.n_gid = iattr->ia_gid;
1121 	}
1122 
1123 	/* Write all dirty data */
1124 	if (S_ISREG(dentry->d_inode->i_mode))
1125 		filemap_write_and_wait(dentry->d_inode->i_mapping);
1126 
1127 	retval = p9_client_wstat(fid, &wstat);
1128 	if (retval < 0)
1129 		return retval;
1130 
1131 	if ((iattr->ia_valid & ATTR_SIZE) &&
1132 	    iattr->ia_size != i_size_read(dentry->d_inode))
1133 		truncate_setsize(dentry->d_inode, iattr->ia_size);
1134 
1135 	v9fs_invalidate_inode_attr(dentry->d_inode);
1136 
1137 	setattr_copy(dentry->d_inode, iattr);
1138 	mark_inode_dirty(dentry->d_inode);
1139 	return 0;
1140 }
1141 
1142 /**
1143  * v9fs_stat2inode - populate an inode structure with mistat info
1144  * @stat: Plan 9 metadata (mistat) structure
1145  * @inode: inode to populate
1146  * @sb: superblock of filesystem
1147  *
1148  */
1149 
1150 void
1151 v9fs_stat2inode(struct p9_wstat *stat, struct inode *inode,
1152 	struct super_block *sb)
1153 {
1154 	umode_t mode;
1155 	char ext[32];
1156 	char tag_name[14];
1157 	unsigned int i_nlink;
1158 	struct v9fs_session_info *v9ses = sb->s_fs_info;
1159 	struct v9fs_inode *v9inode = V9FS_I(inode);
1160 
1161 	set_nlink(inode, 1);
1162 
1163 	inode->i_atime.tv_sec = stat->atime;
1164 	inode->i_mtime.tv_sec = stat->mtime;
1165 	inode->i_ctime.tv_sec = stat->mtime;
1166 
1167 	inode->i_uid = v9ses->dfltuid;
1168 	inode->i_gid = v9ses->dfltgid;
1169 
1170 	if (v9fs_proto_dotu(v9ses)) {
1171 		inode->i_uid = stat->n_uid;
1172 		inode->i_gid = stat->n_gid;
1173 	}
1174 	if ((S_ISREG(inode->i_mode)) || (S_ISDIR(inode->i_mode))) {
1175 		if (v9fs_proto_dotu(v9ses) && (stat->extension[0] != '\0')) {
1176 			/*
1177 			 * Hadlink support got added later to
1178 			 * to the .u extension. So there can be
1179 			 * server out there that doesn't support
1180 			 * this even with .u extension. So check
1181 			 * for non NULL stat->extension
1182 			 */
1183 			strlcpy(ext, stat->extension, sizeof(ext));
1184 			/* HARDLINKCOUNT %u */
1185 			sscanf(ext, "%13s %u", tag_name, &i_nlink);
1186 			if (!strncmp(tag_name, "HARDLINKCOUNT", 13))
1187 				set_nlink(inode, i_nlink);
1188 		}
1189 	}
1190 	mode = p9mode2perm(v9ses, stat);
1191 	mode |= inode->i_mode & ~S_IALLUGO;
1192 	inode->i_mode = mode;
1193 	i_size_write(inode, stat->length);
1194 
1195 	/* not real number of blocks, but 512 byte ones ... */
1196 	inode->i_blocks = (i_size_read(inode) + 512 - 1) >> 9;
1197 	v9inode->cache_validity &= ~V9FS_INO_INVALID_ATTR;
1198 }
1199 
1200 /**
1201  * v9fs_qid2ino - convert qid into inode number
1202  * @qid: qid to hash
1203  *
1204  * BUG: potential for inode number collisions?
1205  */
1206 
1207 ino_t v9fs_qid2ino(struct p9_qid *qid)
1208 {
1209 	u64 path = qid->path + 2;
1210 	ino_t i = 0;
1211 
1212 	if (sizeof(ino_t) == sizeof(path))
1213 		memcpy(&i, &path, sizeof(ino_t));
1214 	else
1215 		i = (ino_t) (path ^ (path >> 32));
1216 
1217 	return i;
1218 }
1219 
1220 /**
1221  * v9fs_readlink - read a symlink's location (internal version)
1222  * @dentry: dentry for symlink
1223  * @buffer: buffer to load symlink location into
1224  * @buflen: length of buffer
1225  *
1226  */
1227 
1228 static int v9fs_readlink(struct dentry *dentry, char *buffer, int buflen)
1229 {
1230 	int retval;
1231 
1232 	struct v9fs_session_info *v9ses;
1233 	struct p9_fid *fid;
1234 	struct p9_wstat *st;
1235 
1236 	p9_debug(P9_DEBUG_VFS, " %s\n", dentry->d_name.name);
1237 	retval = -EPERM;
1238 	v9ses = v9fs_dentry2v9ses(dentry);
1239 	fid = v9fs_fid_lookup(dentry);
1240 	if (IS_ERR(fid))
1241 		return PTR_ERR(fid);
1242 
1243 	if (!v9fs_proto_dotu(v9ses))
1244 		return -EBADF;
1245 
1246 	st = p9_client_stat(fid);
1247 	if (IS_ERR(st))
1248 		return PTR_ERR(st);
1249 
1250 	if (!(st->mode & P9_DMSYMLINK)) {
1251 		retval = -EINVAL;
1252 		goto done;
1253 	}
1254 
1255 	/* copy extension buffer into buffer */
1256 	retval = min(strlen(st->extension)+1, (size_t)buflen);
1257 	memcpy(buffer, st->extension, retval);
1258 
1259 	p9_debug(P9_DEBUG_VFS, "%s -> %s (%.*s)\n",
1260 		 dentry->d_name.name, st->extension, buflen, buffer);
1261 
1262 done:
1263 	p9stat_free(st);
1264 	kfree(st);
1265 	return retval;
1266 }
1267 
1268 /**
1269  * v9fs_vfs_follow_link - follow a symlink path
1270  * @dentry: dentry for symlink
1271  * @nd: nameidata
1272  *
1273  */
1274 
1275 static void *v9fs_vfs_follow_link(struct dentry *dentry, struct nameidata *nd)
1276 {
1277 	int len = 0;
1278 	char *link = __getname();
1279 
1280 	p9_debug(P9_DEBUG_VFS, "%s\n", dentry->d_name.name);
1281 
1282 	if (!link)
1283 		link = ERR_PTR(-ENOMEM);
1284 	else {
1285 		len = v9fs_readlink(dentry, link, PATH_MAX);
1286 
1287 		if (len < 0) {
1288 			__putname(link);
1289 			link = ERR_PTR(len);
1290 		} else
1291 			link[min(len, PATH_MAX-1)] = 0;
1292 	}
1293 	nd_set_link(nd, link);
1294 
1295 	return NULL;
1296 }
1297 
1298 /**
1299  * v9fs_vfs_put_link - release a symlink path
1300  * @dentry: dentry for symlink
1301  * @nd: nameidata
1302  * @p: unused
1303  *
1304  */
1305 
1306 void
1307 v9fs_vfs_put_link(struct dentry *dentry, struct nameidata *nd, void *p)
1308 {
1309 	char *s = nd_get_link(nd);
1310 
1311 	p9_debug(P9_DEBUG_VFS, " %s %s\n",
1312 		 dentry->d_name.name, IS_ERR(s) ? "<error>" : s);
1313 	if (!IS_ERR(s))
1314 		__putname(s);
1315 }
1316 
1317 /**
1318  * v9fs_vfs_mkspecial - create a special file
1319  * @dir: inode to create special file in
1320  * @dentry: dentry to create
1321  * @mode: mode to create special file
1322  * @extension: 9p2000.u format extension string representing special file
1323  *
1324  */
1325 
1326 static int v9fs_vfs_mkspecial(struct inode *dir, struct dentry *dentry,
1327 	u32 perm, const char *extension)
1328 {
1329 	struct p9_fid *fid;
1330 	struct v9fs_session_info *v9ses;
1331 
1332 	v9ses = v9fs_inode2v9ses(dir);
1333 	if (!v9fs_proto_dotu(v9ses)) {
1334 		p9_debug(P9_DEBUG_ERROR, "not extended\n");
1335 		return -EPERM;
1336 	}
1337 
1338 	fid = v9fs_create(v9ses, dir, dentry, (char *) extension, perm,
1339 								P9_OREAD);
1340 	if (IS_ERR(fid))
1341 		return PTR_ERR(fid);
1342 
1343 	v9fs_invalidate_inode_attr(dir);
1344 	p9_client_clunk(fid);
1345 	return 0;
1346 }
1347 
1348 /**
1349  * v9fs_vfs_symlink - helper function to create symlinks
1350  * @dir: directory inode containing symlink
1351  * @dentry: dentry for symlink
1352  * @symname: symlink data
1353  *
1354  * See Also: 9P2000.u RFC for more information
1355  *
1356  */
1357 
1358 static int
1359 v9fs_vfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1360 {
1361 	p9_debug(P9_DEBUG_VFS, " %lu,%s,%s\n",
1362 		 dir->i_ino, dentry->d_name.name, symname);
1363 
1364 	return v9fs_vfs_mkspecial(dir, dentry, P9_DMSYMLINK, symname);
1365 }
1366 
1367 /**
1368  * v9fs_vfs_link - create a hardlink
1369  * @old_dentry: dentry for file to link to
1370  * @dir: inode destination for new link
1371  * @dentry: dentry for link
1372  *
1373  */
1374 
1375 static int
1376 v9fs_vfs_link(struct dentry *old_dentry, struct inode *dir,
1377 	      struct dentry *dentry)
1378 {
1379 	int retval;
1380 	char *name;
1381 	struct p9_fid *oldfid;
1382 
1383 	p9_debug(P9_DEBUG_VFS, " %lu,%s,%s\n",
1384 		 dir->i_ino, dentry->d_name.name, old_dentry->d_name.name);
1385 
1386 	oldfid = v9fs_fid_clone(old_dentry);
1387 	if (IS_ERR(oldfid))
1388 		return PTR_ERR(oldfid);
1389 
1390 	name = __getname();
1391 	if (unlikely(!name)) {
1392 		retval = -ENOMEM;
1393 		goto clunk_fid;
1394 	}
1395 
1396 	sprintf(name, "%d\n", oldfid->fid);
1397 	retval = v9fs_vfs_mkspecial(dir, dentry, P9_DMLINK, name);
1398 	__putname(name);
1399 	if (!retval) {
1400 		v9fs_refresh_inode(oldfid, old_dentry->d_inode);
1401 		v9fs_invalidate_inode_attr(dir);
1402 	}
1403 clunk_fid:
1404 	p9_client_clunk(oldfid);
1405 	return retval;
1406 }
1407 
1408 /**
1409  * v9fs_vfs_mknod - create a special file
1410  * @dir: inode destination for new link
1411  * @dentry: dentry for file
1412  * @mode: mode for creation
1413  * @rdev: device associated with special file
1414  *
1415  */
1416 
1417 static int
1418 v9fs_vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t rdev)
1419 {
1420 	struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dir);
1421 	int retval;
1422 	char *name;
1423 	u32 perm;
1424 
1425 	p9_debug(P9_DEBUG_VFS, " %lu,%s mode: %hx MAJOR: %u MINOR: %u\n",
1426 		 dir->i_ino, dentry->d_name.name, mode,
1427 		 MAJOR(rdev), MINOR(rdev));
1428 
1429 	if (!new_valid_dev(rdev))
1430 		return -EINVAL;
1431 
1432 	name = __getname();
1433 	if (!name)
1434 		return -ENOMEM;
1435 	/* build extension */
1436 	if (S_ISBLK(mode))
1437 		sprintf(name, "b %u %u", MAJOR(rdev), MINOR(rdev));
1438 	else if (S_ISCHR(mode))
1439 		sprintf(name, "c %u %u", MAJOR(rdev), MINOR(rdev));
1440 	else if (S_ISFIFO(mode))
1441 		*name = 0;
1442 	else if (S_ISSOCK(mode))
1443 		*name = 0;
1444 	else {
1445 		__putname(name);
1446 		return -EINVAL;
1447 	}
1448 
1449 	perm = unixmode2p9mode(v9ses, mode);
1450 	retval = v9fs_vfs_mkspecial(dir, dentry, perm, name);
1451 	__putname(name);
1452 
1453 	return retval;
1454 }
1455 
1456 int v9fs_refresh_inode(struct p9_fid *fid, struct inode *inode)
1457 {
1458 	int umode;
1459 	dev_t rdev;
1460 	loff_t i_size;
1461 	struct p9_wstat *st;
1462 	struct v9fs_session_info *v9ses;
1463 
1464 	v9ses = v9fs_inode2v9ses(inode);
1465 	st = p9_client_stat(fid);
1466 	if (IS_ERR(st))
1467 		return PTR_ERR(st);
1468 	/*
1469 	 * Don't update inode if the file type is different
1470 	 */
1471 	umode = p9mode2unixmode(v9ses, st, &rdev);
1472 	if ((inode->i_mode & S_IFMT) != (umode & S_IFMT))
1473 		goto out;
1474 
1475 	spin_lock(&inode->i_lock);
1476 	/*
1477 	 * We don't want to refresh inode->i_size,
1478 	 * because we may have cached data
1479 	 */
1480 	i_size = inode->i_size;
1481 	v9fs_stat2inode(st, inode, inode->i_sb);
1482 	if (v9ses->cache)
1483 		inode->i_size = i_size;
1484 	spin_unlock(&inode->i_lock);
1485 out:
1486 	p9stat_free(st);
1487 	kfree(st);
1488 	return 0;
1489 }
1490 
1491 static const struct inode_operations v9fs_dir_inode_operations_dotu = {
1492 	.create = v9fs_vfs_create,
1493 	.lookup = v9fs_vfs_lookup,
1494 	.atomic_open = v9fs_vfs_atomic_open,
1495 	.symlink = v9fs_vfs_symlink,
1496 	.link = v9fs_vfs_link,
1497 	.unlink = v9fs_vfs_unlink,
1498 	.mkdir = v9fs_vfs_mkdir,
1499 	.rmdir = v9fs_vfs_rmdir,
1500 	.mknod = v9fs_vfs_mknod,
1501 	.rename = v9fs_vfs_rename,
1502 	.getattr = v9fs_vfs_getattr,
1503 	.setattr = v9fs_vfs_setattr,
1504 };
1505 
1506 static const struct inode_operations v9fs_dir_inode_operations = {
1507 	.create = v9fs_vfs_create,
1508 	.lookup = v9fs_vfs_lookup,
1509 	.atomic_open = v9fs_vfs_atomic_open,
1510 	.unlink = v9fs_vfs_unlink,
1511 	.mkdir = v9fs_vfs_mkdir,
1512 	.rmdir = v9fs_vfs_rmdir,
1513 	.mknod = v9fs_vfs_mknod,
1514 	.rename = v9fs_vfs_rename,
1515 	.getattr = v9fs_vfs_getattr,
1516 	.setattr = v9fs_vfs_setattr,
1517 };
1518 
1519 static const struct inode_operations v9fs_file_inode_operations = {
1520 	.getattr = v9fs_vfs_getattr,
1521 	.setattr = v9fs_vfs_setattr,
1522 };
1523 
1524 static const struct inode_operations v9fs_symlink_inode_operations = {
1525 	.readlink = generic_readlink,
1526 	.follow_link = v9fs_vfs_follow_link,
1527 	.put_link = v9fs_vfs_put_link,
1528 	.getattr = v9fs_vfs_getattr,
1529 	.setattr = v9fs_vfs_setattr,
1530 };
1531 
1532